Near-infrared Spectroscopy of GRB Host Galaxies at z >~ 1.5: Insights
into Host Galaxy Dynamics and Interpretations of Afterglow Absorption Spectra
H. Chen. (2011)cite arxiv:1110.0487Comment: 10 pages, 6 figures, accepted for publication in MNRAS.
Abstract
This paper presents near-infrared echellette spectra of faint galaxies in the
fields around GRB 050820A at redshift z=2.613 and GRB 060418 at z=1.490. The
spectroscopic data show that both GRBs originate in a dynamic environment of
interacting galaxies separated by < 15 h^-1 kpc in projected distance and
|dv| <~ 60 km/s in line-of-sight velocity. The optical afterglows revealed in
early-epoch Hubble Space Telescope images are at least 2.5 h^-1 kpc (or 0.4")
away from the high surface brightness regions of the interacting members,
indicating that the GRB events occurred either in the outskirts of a compact
star-forming galaxy or in a low surface brightness satellite. Comparisons of
the systemic redshifts of the host galaxies and the velocity distribution of
absorbing clouds revealed in early-time afterglow spectra further show that the
majority of the absorbing clouds are redshifted from these compact star-forming
galaxies. These include the gas producing fine-structure absorption lines at
physical distances d ~ a few x 100 pc from the GRB afterglow. The lack of
blueshifted absorbing clouds and the spatial offset of the GRB event from the
star-forming regions make it difficult to attribute the observed large velocity
spread (~ 200-400 km/s) of absorbing gas in the GRB host to galactic-scale
outflows. We consider a scenario in which the GRB event occurred in a dwarf
satellite of the interacting group and interpret the broad absorption
signatures in the afterglow spectra as a collective effect of the turbulent
halo gas and the host star-forming ISM. We briefly discuss the implications for
the absorption properties observed in the afterglow spectra.
Description
[1110.0487] Near-infrared Spectroscopy of GRB Host Galaxies at z >~ 1.5: Insights into Host Galaxy Dynamics and Interpretations of Afterglow Absorption Spectra
%0 Generic
%1 Chen2011
%A Chen, Hsiao-Wen
%D 2011
%K galaxy grb host satellites
%T Near-infrared Spectroscopy of GRB Host Galaxies at z >~ 1.5: Insights
into Host Galaxy Dynamics and Interpretations of Afterglow Absorption Spectra
%U http://arxiv.org/abs/1110.0487
%X This paper presents near-infrared echellette spectra of faint galaxies in the
fields around GRB 050820A at redshift z=2.613 and GRB 060418 at z=1.490. The
spectroscopic data show that both GRBs originate in a dynamic environment of
interacting galaxies separated by < 15 h^-1 kpc in projected distance and
|dv| <~ 60 km/s in line-of-sight velocity. The optical afterglows revealed in
early-epoch Hubble Space Telescope images are at least 2.5 h^-1 kpc (or 0.4")
away from the high surface brightness regions of the interacting members,
indicating that the GRB events occurred either in the outskirts of a compact
star-forming galaxy or in a low surface brightness satellite. Comparisons of
the systemic redshifts of the host galaxies and the velocity distribution of
absorbing clouds revealed in early-time afterglow spectra further show that the
majority of the absorbing clouds are redshifted from these compact star-forming
galaxies. These include the gas producing fine-structure absorption lines at
physical distances d ~ a few x 100 pc from the GRB afterglow. The lack of
blueshifted absorbing clouds and the spatial offset of the GRB event from the
star-forming regions make it difficult to attribute the observed large velocity
spread (~ 200-400 km/s) of absorbing gas in the GRB host to galactic-scale
outflows. We consider a scenario in which the GRB event occurred in a dwarf
satellite of the interacting group and interpret the broad absorption
signatures in the afterglow spectra as a collective effect of the turbulent
halo gas and the host star-forming ISM. We briefly discuss the implications for
the absorption properties observed in the afterglow spectra.
@misc{Chen2011,
abstract = { This paper presents near-infrared echellette spectra of faint galaxies in the
fields around GRB 050820A at redshift z=2.613 and GRB 060418 at z=1.490. The
spectroscopic data show that both GRBs originate in a dynamic environment of
interacting galaxies separated by < 15 h^{-1} kpc in projected distance and
|dv| <~ 60 km/s in line-of-sight velocity. The optical afterglows revealed in
early-epoch Hubble Space Telescope images are at least 2.5 h^{-1} kpc (or 0.4")
away from the high surface brightness regions of the interacting members,
indicating that the GRB events occurred either in the outskirts of a compact
star-forming galaxy or in a low surface brightness satellite. Comparisons of
the systemic redshifts of the host galaxies and the velocity distribution of
absorbing clouds revealed in early-time afterglow spectra further show that the
majority of the absorbing clouds are redshifted from these compact star-forming
galaxies. These include the gas producing fine-structure absorption lines at
physical distances d ~ a few x 100 pc from the GRB afterglow. The lack of
blueshifted absorbing clouds and the spatial offset of the GRB event from the
star-forming regions make it difficult to attribute the observed large velocity
spread (~ 200-400 km/s) of absorbing gas in the GRB host to galactic-scale
outflows. We consider a scenario in which the GRB event occurred in a dwarf
satellite of the interacting group and interpret the broad absorption
signatures in the afterglow spectra as a collective effect of the turbulent
halo gas and the host star-forming ISM. We briefly discuss the implications for
the absorption properties observed in the afterglow spectra.
},
added-at = {2011-10-05T22:00:52.000+0200},
author = {Chen, Hsiao-Wen},
biburl = {https://www.bibsonomy.org/bibtex/27e227b98d2f018fac068e5de2a6b185e/miki},
description = {[1110.0487] Near-infrared Spectroscopy of GRB Host Galaxies at z >~ 1.5: Insights into Host Galaxy Dynamics and Interpretations of Afterglow Absorption Spectra},
interhash = {8b8bdad460f675fed811eaf12a926c99},
intrahash = {7e227b98d2f018fac068e5de2a6b185e},
keywords = {galaxy grb host satellites},
note = {cite arxiv:1110.0487Comment: 10 pages, 6 figures, accepted for publication in MNRAS},
timestamp = {2011-10-05T22:00:52.000+0200},
title = {Near-infrared Spectroscopy of GRB Host Galaxies at z >~ 1.5: Insights
into Host Galaxy Dynamics and Interpretations of Afterglow Absorption Spectra},
url = {http://arxiv.org/abs/1110.0487},
year = 2011
}